Tool traversing mechanism controlled by templates or patterns



S p 1 A. E. LAWS 3,400,608

TOOL TRAVERSING MECHANISM CONTROLLED I BY TEMPLATES OR PATTERNS Filed Aug. 22, 1966 HOCDCOOMO'I He. J.

United States Patent 3,400,608 TOOL TRAVERSING MEHANHSM (CONTROLLED BY TEMPLATES OR PATTERNS Arthur Ernest Laws, 53 Beaumont Ave., St. Albans, Hertfordshire, England Filed Aug. 22, 1966, Ser. No. 574,142 Claims priority, application Great Britain, Aug. 23, 1965, 36,143/ 65 2 Claims. (Cl. 74-569) This invention relates to template follower mechanisms, and is particularly, but not exclusively applicable to such mechanisms for use in automatic sewing machines.

Mechanisms of this general kind are known in which a follower comprising a motor driven roller is caused to bear against the template, so that the roller rolls itself along the template. Difliculty can be experienced, however, with the roller jamming in an internal corner of the template, and the present invention provides a mechanism designed to overcome this problem.

Accordingly, the invention provides a template follower mechanism comprising a motor driven roller which is caused to bear against a template, a gear pinion also rotatably driven and coaxial with the roller, a gear member mounted adjacent an internal corner of the template for engagement by the pinion when the roller enters the corner, and a lost motion connection to ensure that the roller will dwell in the corner before the gear member becomes elfective to act as an abutment against which the pinion can work to drive the roller out of the corner.

This arrangement ensures not only that the follower will be positively driven out of the corner, but that the follower dwells in the corner momentarily. This is of particular benefit in relation to sewing machines, for it assists in ensuring that at least one stitch is formed at the corresponding corner of the work.

One form of template follower mechanism is described below, by way of example, with reference to the accompanying drawings, in which:

FIGURE 1 is a plan view of a template;

FIGURE 2 is a plan view of part of the same template drawn to a larger scale and also showing the follower; and

FIGURE 3 is a sectional elevation, on an even larger scale, on the line IIIIII of FIGURE 2.

The particular mechanism illustrated in primarily intended for use with a sewing machine which we have previously proposed, the machine including a work holder movable relative to the needle of the machine in two mutually transverse directions by means of a pair of fluid pressure operated servomotors under the control of a control valve which is mechanically linked to a template follower. The follower comprises a motor driven roller which is caused to bear against and roll along the contour of a template whose profile corresponds to the desired line of stitching to be effected.

Referring now to the drawings, the template 1 coopcrates with a roller 2 secured to a motor driven spindle 3 which also carries a gear pinion 4 rotatable with the spindle. Either the template or the roller is magnetized, so that the magnetic attraction causes the roller to bear against the template. Mounted adjacent each of two internal corners is a gear member 6, positioned to mesh with the pinion 4 when the roller 2 enters the internal corner.

In this embodiment, the gear member 6 takes the form of a complete gear wheel rotatably mounted upon a spacer bush 7 fitted over a pin 8 fixed in a base plate 9 secured to the template. The pin has a head 11, and the bush is clamped against rotation between this head and the plate 9. The head 11 carries a stop pin 12 extending into a slot 13 in the gear wheel 6, the width of the slot being several times the diameter of the pin, so that the gear is capable 3,400,608 Patented Sept. 10, 1968 of a limited degree of angular displacement. A second slot 14 in the gear Wheel 6 receives and anchors one end 17 of a helical coil spring 18, whose other end 19 is similarly received in a slot 21 at the lower end of the bush 7. The spring is preloaded, so that the gear wheel 6 is normally held at the limit of its counterclockwise travel, as viewed in FIGURES 1 and 2.

In operation, when the follower reaches the corner the driven pinion 4 engages the gear wheel 6, but the follower remains stationary in the corner while the wheel is rotated in the clockwise direction, against the action of its spring 18. Upon the side of the slot 13 engaging the stop pin 12, the gear wheel 6 becomes effective to act as a solid abutment against which the pinion can Work to drive the follower out of the corner. The period of dwell of the follower in the corner may be very brief, for example in the order of one twentieth of a second, but this is sufficient to ensure that at least one stitch is formed at the corresponding corner of the Work. This is extremely critical in the case of the stitching, for example, of a shirt collar at the acute angle at the point of the collar.

The brief dwell of the follower has a further beneficial effect in that it allows the movement of the work holder to catch up with the movement of the template follower, thereby avoiding the undesirable deviations from the desired path which may result from the sudden reversal of movement of the template follower at the acute angled corner.

Many variations and modifications will of course be possible within the scope of the invention. For example, the gear member is not essentially in the form of a gear wheel but could for example be constituted by a rectilinear rack or a gear sector. Again, the lost motion connection need not be between the toothed member and its mounting but could for example be between the gear pinion and the member which drives it.

It will be appreciated that the above described mechanism could be used in many different forms of machines apart from sewing machines, and the term template, as used in the appended claims wiil include equivalent members such as cams or other patterns.

I claim:

1. A template follower mechanism comprising a template having an internal corner, a motor driven roller which is caused to bear against the template, a rotatably driven gear pinion coaxial with said roller, a gear member mounted adjacent said internal corner of said template for engagement by said pinion when said roller enters said corner, and lost-motion connection means operative to ensure that said roller will dwell in said center after engagement of said pinion with said gear member prior to said gear member becoming effective to act as an abutment against which said pinion can work to drive said roller out of said corner.

2. Mechanism in accordance with claim 1, wherein said pinion is fast with said roller for rotation therewith, and comprising means mounting said gear member on said template for displacement relative thereto between a first and second spaced position, each determined by stop means, and resilient means biassing said member towards said first position, said pinion being operative, upon engagement with said gear member, to move said member to said second position.

References Cited FOREIGN PATENTS 23,015 10/1963 Japan. 293,052 7/1965 Netherlands.

FRED C. MATTERN, JR., Primary Examiner.

F. D. SHOEMAKER, Assistant Examiner. 

1. A TEMPLATE FOLLOWER MECHANISM COMPRISING A TEMPLATE HAVING AN INTERNAL CORNER, A MOTOR DRIVEN ROLLER WHICH IS CAUSED TO BEAR AGAINST THE TEMPLATE, A ROTATABLY DRIVEN GEAR PINION COAXIAL WITH SAID ROLLER, A GEAR MEMBER MOUNTED ADJACENT SAID INTERNAL CORNER OF SAID TEMPLATE FOR ENGAGEMENT BY SAID PINION WHEN SAID ROLLER ENTERS SAID CORNER, AND LOST-MOTION CONNECTION MEANS OPERATIVE TO ENSURE THAT SAID ROLLER WILL DWELL IN SAID CORNER AFTER ENGAGEMENT OF SAID PINION WITH SAID GEAR MEMBER PRIOR TO SAID GEAR MEMBER BECOMING EFFECTIVE TO ACT AS AN ABUTMENT AGAINST WHICH SAID PINION CAN WORK TO DRIVE SAID ROLLER OUT OF SAID CORNER. 